A film for use on a copper clad board for integrated circuits

Abstract

The present application relates to copper-clad plate technical field, specifically to a kind of film used on integrated circuit copper-clad plate.The film includes polyimide main body layer and only forms copper side interface layer on its side;Interface layer is formed by coating dianhydride end group rich polyamide acid under specific residual solvent content and heat imidization with main body layer;Copper side outer surface is treated with hydrochloric acid dopamine / triethylamine to enrich catechol end group, and active interface is formed by copper (II) salt loading, ethylenediaminetetraacetate complex stripping.The present application improves the initial and wet heat stripping strength of film and low profile copper foil by asymmetric interface design and time-sequenced post-processing process without increasing the polarity of main body layer, while ensuring that the material has lower 10GHz dielectric loss and excellent volume resistivity, suitable for high-end high-frequency integrated circuit packaging field.

Description

Technical Field

[0001] This invention relates to the field of copper clad laminate technology, and more particularly to a thin film used in copper clad laminates for integrated circuits. Background Technology

[0002] As integrated circuit operating frequencies shift towards higher millimeter-wave bands, the signal transmission speed and integrity of copper-clad laminates increasingly rely on the low dielectric loss characteristics of the dielectric material. Currently, the industry commonly uses fluorinated polyimide as the matrix resin, effectively reducing the dielectric constant and loss factor of the dielectric layer by utilizing the low polarity of the carbon-fluorine bond, thus meeting the physical performance requirements for high-frequency signal transmission. However, while the low-polarity molecular structure design reduces dielectric loss, it also weakens the physicochemical interaction at the interface between polyimide and copper foil, making it difficult to improve peel strength.

[0003] To address the issue of insufficient bonding strength, existing technologies often employ physical roughening methods to increase the surface roughness of the copper foil or introduce highly polar adhesive layers. However, these methods have significant drawbacks in high-frequency environments: a rough copper surface easily induces signal scattering and insertion loss, while introducing additional polar functional groups or thick adhesive layers significantly increases the overall dielectric loss of the dielectric, and may even degrade volume resistivity and hygrothermal stability. Furthermore, simple interfacial metal coordination modification without an effective free ion control mechanism can easily lead to insulation failure. How to achieve a highly reliable interfacial bond between polyimide and low-profile copper foil while maintaining low dielectric loss and high insulation has always been a core technological bottleneck restricting the development of high-end high-frequency copper-clad laminates. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a thin film for use on copper-clad laminates of integrated circuits, so as to solve the problems of insufficient interfacial adhesion and poor damp heat reliability of polyimide film with low dielectric loss and high insulation, while maintaining the low dielectric loss and high insulation of polyimide film.

[0005] To achieve the above objectives, the present invention provides a thin film for use on a copper-clad laminate of an integrated circuit, comprising a polyimide host layer and a copper-side interface layer formed only on one side of the polyimide host layer. Based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, the polyimide host layer is formed by thermal imidization of a host layer polyamic acid comprising 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 55.5-83.2 parts by weight of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 36.8-55.1 parts by weight of 3,3',4,4'-biphenyltetracarboxylic dianhydride; Based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, the copper-side interface layer is formed of a dianhydride-end-rich interface layer polyamic acid comprising 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 58.4-100 parts by weight of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 44.1-57.8 parts by weight of 3,3',4,4'-biphenyltetracarboxylic dianhydride; The copper-side interface layer is formed by coating the dianhydride-end-group-enriched interface layer polyamic acid on one side of the pre-baked film and thermally imidizing it together with the polyamic acid of the main layer when the residual solvent content of the pre-baked film formed by the polyamic acid of the main layer is 12%-18%. The outer surface of the copper-side interface layer is an interface-activated surface formed by enriching catechol end groups through treatment with dopamine / triethylamine hydrochloride after thermal imidization, and then undergoing ethylenediaminetetraacetic acid complexation and exfoliation treatment after loading with copper(II) salt.

[0006] Preferably, the molar ratio of total dianhydride monomer to 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl in the main polyamic acid layer is 0.98-1.02:1, and the molar ratio of total dianhydride monomer to 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl in the dianhydride-enriched interface polyamic acid layer is 1.05-1.20:1.

[0007] Preferably, the main layer polyamic acid is obtained by polymerization of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride in anhydrous 1-methyl-2-pyrrolidone; and the anhydrous 1-methyl-2-pyrrolidone is 1193-1249 parts by weight based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

[0008] Preferably, the dianhydride-terminated interfacial polyamic acid is obtained by polymerization of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride in anhydrous 1-methyl-2-pyrrolidone; and the anhydrous 1-methyl-2-pyrrolidone comprises 6731-10596 parts by weight, based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

[0009] Preferably, the pre-baked film is obtained by casting the main layer of polyamic acid into a film, and then heating it sequentially at 80°C for 25-35 minutes and at 120°C for 15-25 minutes.

[0010] Preferably, the coating mass ratio of the dianhydride-end-rich interface layer polyamic acid to the host layer polyamic acid is 60-120:2500, and the dianhydride-end-rich interface layer polyamic acid is coated on one side of the pre-baked film using a 5-15μm wire rod.

[0011] Preferably, the co-thermal imidization process includes: holding at 80°C for 30 min, holding at 150°C for 30 min, holding at 220°C for 30 min, holding at 300°C for 30 min, and holding at 310°C for 20 min.

[0012] Preferably, the treatment solution used for the dopamine / triethylamine hydrochloride treatment comprises anhydrous ethanol, anhydrous 1-methyl-2-pyrrolidone, dopamine hydrochloride, and triethylamine; and the mass ratio of the anhydrous ethanol, anhydrous 1-methyl-2-pyrrolidone, dopamine hydrochloride, and triethylamine is 70000:30000:300-700:160-400.

[0013] Preferably, the dopamine / triethylamine hydrochloride treatment is performed by: coating the outer surface of the copper-side interface layer with the copper-side interface layer facing upwards, and maintaining it at 35-55°C under dry nitrogen protection for 3-8 minutes.

[0014] Preferably, the copper(II) salt is copper(II) acetate monohydrate, and the ethylenediaminetetraacetic acid salt is ethylenediaminetetraacetic acid disodium salt dihydrate.

[0015] Preferably, the copper(II) salt loading treatment is performed by adding 10-40 parts by weight of copper(II) acetate monohydrate to a mixture of 80,000 parts by weight of anhydrous ethanol and 20,000 parts by weight of deionized water to form a copper(II) acetate monohydrate treatment solution, coating the copper(II) acetate monohydrate treatment solution onto the outer surface enriched with catechol end groups and rinsing after holding for 30-90 seconds.

[0016] Preferably, the ethylenediaminetetraacetic acid (EDTA) complexation and stripping treatment is performed by adding 5-20 parts by weight of EDTA disodium salt dihydrate to 100,000 parts by weight of deionized water to form an EDTA disodium salt dihydrate treatment solution, applying the EDTA disodium salt dihydrate treatment solution to the outer surface after copper(II) salt loading treatment and maintaining it for 20-60 seconds before rinsing.

[0017] The beneficial effects of this invention are: (1) This invention achieves a molecular-level gradient transition in the interface region by coating a dianhydride-rich interface layer and co-imidizing it during a specific residual solvent window period (12%-18%) in the pre-baking of the main layer. Data shows that this asymmetric structural design avoids high polarity across the entire layer, resulting in a loss tangent of only 0.0036-0.0048 in the 10GHz band for Examples 1-5, while the initial 90° peel strength is as high as 0.98-1.36 N / mm, successfully solving the material design paradox between low dielectric loss and high peel strength.

[0018] (2) This invention constructs a confined catechol coordination network at the interface by performing thermal imidization followed by single-sided dopamine / triethylamine hydrochloride treatment on the copper-side interface, combined with a time-sequential post-treatment process of copper(II) salt loading and ethylenediaminetetraacetic acid complexation and peeling. Test results show that the composite treated by this process exhibits excellent peel strength retention after wet heat treatment. In Example 3, the peel strength still reached 1.18 N / mm after treatment at 85℃ / 85%RH for 168 hours, which is much higher than the scheme in the comparative example that relies solely on copper species residue or ordinary passivation treatment, effectively solving the interface failure problem under high temperature and high humidity conditions.

[0019] (3) By strictly limiting interface activation to the copper side and combining it with a weak passivation treatment of the copper foil surface, this invention minimizes the interference of polar groups and free metal ions on the electrical insulation performance of the main layer. Performance tests confirm that the volume resistivity of Examples 1-5 remains at 7.2 × 10⁻⁶. 16 -9.1×10 16 With a high Ω·cm range and a linear thermal expansion coefficient as low as 20.8-23.2ppm / ℃, it significantly improves the dimensional stability and long-term operational reliability of integrated circuit copper-clad laminates while ensuring the integrity of high-frequency signals. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0021] The low-profile electrolytic copper foil used in the examples and comparative examples is Mitsui Metals 3EC-M2S-VLP type low-profile electrolytic copper foil with a thickness of 18μm and a ten-point average roughness of 1.5μm on the surface to be pressed. Example 1:

[0022] This embodiment takes the preparation of a 100mm×100mm single-sided lamination evaluation polyimide film and copper foil composite as an example, and the continuous coating production is scaled up proportionally according to the area.

[0023] Step 1: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried separately in an 80°C vacuum oven for 4 hours. After cooling, they were used under a dry nitrogen atmosphere. 39066 mg of anhydrous 1-methyl-2-pyrrolidone was added to a three-necked flask that had been dried at 120°C for 2 hours and cooled to room temperature. The solvent temperature was controlled between 5°C and 10°C. 3202 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added, and the mixture was stirred for 60 minutes until the solid was completely dissolved. Subsequently, 2221 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 1471 mg of 1471 mg of 4,4'-diaminobiphenyl were added in three batches. 3,3',4,4'-Biphenyltetracarboxylic dianhydride was added to each batch and stirred for 30 minutes before adding the next batch. After all the materials were added, the temperature was raised to 25°C and stirred for 12 hours to obtain the polyamic acid solution for the main layer. Step 2: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried in a vacuum oven at 80°C for 4 hours. After cooling, they were used under the protection of dry nitrogen. 28587 mg of anhydrous 1-methyl-2-pyrrolidone was added to another three-necked flask purged with dry nitrogen. The temperature was controlled at 5°C to 10°C. 320 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added and stirred for 40 min. Then 235 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 178 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added and stirred at 25°C for 8 hours to obtain an interfacial polyamic acid solution. Step 3: Take 2500 mg of the main layer polyamic acid solution obtained in Step 1, invert it onto a glass plate that has been cleaned with anhydrous ethanol and dried at 120°C for 30 min, and cast it into a film in the same direction with a 200 μm doctor blade gap. Remove the excess solution with the doctor blade and do not recycle it. Place the cast film on an 80°C hot stage and heat it for 30 min, then place it on a 120°C hot stage and heat it for 20 min. The residual solvent content of the pre-baked film is measured to be 15% by weighing. Then take 100 mg of the interface layer polyamic acid solution obtained in Step 2, coat it once on the upper surface of the pre-baked film with a 10 μm wire rod, and heat it at 80°C for 10 min to obtain an asymmetric laminated wet film with dianhydride end groups enriched in the interface layer polyamic acid on only one side. Step 4: Place the asymmetric laminated wet film obtained in Step 3 along with the glass plate in a nitrogen oven and perform a temperature increase process according to the following steps: 80℃ for 30 min, 150℃ for 30 min, 220℃ for 30 min, 300℃ for 30 min, and 310℃ for 20 min. After the process, cool the film to below 60℃ in a nitrogen atmosphere and peel it off from the glass plate to obtain an asymmetric polyimide film with a thickness of 26.5 μm. Step 5: Add 70,000 mg of anhydrous ethanol, 30,000 mg of anhydrous 1-methyl-2-pyrrolidone, 500 mg of dopamine hydrochloride, and 280 mg of triethylamine to a brown beaker. Stir for 20 min under dry nitrogen protection and at 25°C in the dark to obtain a dopamine treatment solution. With the dianhydride end-group enriched side of the asymmetric polyimide film obtained in Step 4 facing upward, take 1,000 mg of the dopamine treatment solution and evenly coat it on this side. Keep it at 45°C under dry nitrogen protection for 5 min. Then rinse it with 50,000 mg of anhydrous ethanol for the first time, and then rinse it with 50,000 mg of anhydrous ethanol for the second time. After that, vacuum dry at 60°C for 30 min, and then vacuum dry at 150°C for 20 min to obtain a polyimide film with catechol end-group enriched on the copper side. Step 6: Add 20 mg of copper(II) acetate monohydrate to a mixture of 80,000 mg anhydrous ethanol and 20,000 mg deionized water, and stir for 10 min to form a copper(II) acetate monohydrate treatment solution; take 500 mg of the copper(II) acetate monohydrate treatment solution and coat it onto the catechol-terminated side of the film obtained in Step 5, keep it for 60 s, and then rinse with 50,000 mg anhydrous ethanol; then add 10 mg of disodium ethylenediaminetetraacetate dihydrate to 100,000 mg deionized water, and stir for 10 min to form a disodium ethylenediaminetetraacetate dihydrate treatment solution; take 500 mg of the disodium ethylenediaminetetraacetate dihydrate treatment solution and coat it onto the catechol-terminated side treated with copper(II) acetate monohydrate, keep it for 30 s, and then rinse with 100,000 mg deionized water, then rinse with 50,000 mg anhydrous ethanol, and vacuum dry at 80 °C for 20 min; Step 7: Take a 100mm×100mm low-profile electrolytic copper foil, rinse it with 30,000mg of anhydrous ethanol, then rinse it with 100,000mg of deionized water, and dry it at 80℃ for 10min; add 20mg of 1,2,3-benzotriazole to a mixture of 70,000mg of anhydrous ethanol and 30,000mg of deionized water, stir for 10min to form a 1,2,3-benzotriazole treatment solution; immerse the copper foil to be pressed into the 1,2,3-benzotriazole treatment solution for 30s, take it out and rinse it with 20,000mg of anhydrous ethanol, and dry it at 80℃ for 10min; Step 8: Dry the film obtained in Step 6 under vacuum at 120°C for 30 min. Lay the catechol-terminated side treated in Step 6 with the copper foil side to be pressed in Step 7. Place the laminate in a vacuum hot press and evacuate to an absolute pressure below 500 Pa. Preheat at 160°C and 0 MPa for 10 min, then press at 240°C and 2 MPa for 30 min. After pressing, cool to below 80°C while maintaining pressure, and remove to obtain the polyimide film and copper foil composite for integrated circuit copper-clad laminates. Example 2:

[0024] This embodiment takes the preparation of a 100mm×100mm single-sided lamination evaluation polyimide film and copper foil composite as an example, and the continuous coating production is scaled up proportionally according to the area.

[0025] Step 1: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried separately in an 80°C vacuum oven for 4 hours. After cooling, they were used under a dry nitrogen atmosphere. 38216 mg of anhydrous 1-methyl-2-pyrrolidone was added to a three-necked flask that had been dried at 120°C for 2 hours and cooled to room temperature. The solvent temperature was controlled between 5°C and 10°C. 3202 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added, and the mixture was stirred for 60 minutes until the solid was completely dissolved. Subsequently, 1777 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 1765 mg of 1,4'-diaminobiphenyl were added in three batches. 3,3',4,4'-Biphenyltetracarboxylic dianhydride was added to each batch and stirred for 30 minutes before adding the next batch. After all the materials were added, the temperature was raised to 25°C and stirred for 12 hours to obtain the polyamic acid solution for the main layer. Step 2: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried in a vacuum oven at 80°C for 4 hours. After cooling, they were used under the protection of dry nitrogen. 33908 mg of anhydrous 1-methyl-2-pyrrolidone was added to another three-necked flask purged with dry nitrogen. The temperature was controlled at 5°C to 10°C. 320 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added and stirred for 40 min. Then 187 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 185 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added and stirred at 25°C for 8 hours to obtain an interfacial polyamic acid solution. Step 3: Take 2500 mg of the main layer polyamic acid solution obtained in Step 1, invert it onto a glass plate that has been cleaned with anhydrous ethanol and dried at 120°C for 30 min, and cast it into a film in the same direction with a 200 μm doctor blade gap. Remove the excess solution with the doctor blade and do not recycle it. Place the cast film on an 80°C hot stage and heat it for 35 min, then place it on a 120°C hot stage and heat it for 25 min. The residual solvent content of the pre-baked film is measured to be 12% by weighing. Then take 60 mg of the interface layer polyamic acid solution obtained in Step 2, coat it once on the upper surface of the pre-baked film with a 5 μm wire rod, and heat it at 80°C for 10 min to obtain an asymmetric laminated wet film with dianhydride end groups enriched in the interface layer polyamic acid on only one side. Step 4: Place the asymmetric laminated wet film obtained in Step 3 along with the glass plate in a nitrogen oven and heat it according to the following temperature program: 80℃ for 30 min, 150℃ for 30 min, 220℃ for 30 min, 300℃ for 30 min, and 310℃ for 20 min. After the treatment, cool it to below 60℃ in a nitrogen atmosphere and peel the film off the glass plate to obtain an asymmetric polyimide film with a thickness of 25.8 μm. Step 5: Add 70,000 mg of anhydrous ethanol, 30,000 mg of anhydrous 1-methyl-2-pyrrolidone, 300 mg of dopamine hydrochloride, and 160 mg of triethylamine to a brown beaker. Stir for 20 min under dry nitrogen protection and at 25°C in the dark to obtain a dopamine treatment solution. With the dianhydride end-group enriched side of the asymmetric polyimide film obtained in Step 4 facing upward, take 1,000 mg of the dopamine treatment solution and evenly coat it on this side. Keep it at 35°C under dry nitrogen protection for 3 min. Then rinse it with 50,000 mg of anhydrous ethanol for the first time, and then rinse it with 50,000 mg of anhydrous ethanol for the second time. After that, vacuum dry at 60°C for 30 min, and then vacuum dry at 150°C for 20 min to obtain a polyimide film with catechol end-group enriched on the copper side. Step 6: Add 10 mg of copper(II) acetate monohydrate to a mixture of 80,000 mg anhydrous ethanol and 20,000 mg deionized water, and stir for 10 min to form a copper(II) acetate monohydrate treatment solution; take 500 mg of the copper(II) acetate monohydrate treatment solution and coat it onto the catechol-terminated side of the film obtained in Step 5, keep it for 30 s, and then rinse with 50,000 mg anhydrous ethanol; then add 5 mg of disodium ethylenediaminetetraacetate dihydrate to 100,000 mg deionized water, and stir for 10 min to form a disodium ethylenediaminetetraacetate dihydrate treatment solution; take 500 mg of the disodium ethylenediaminetetraacetate dihydrate treatment solution and coat it onto the catechol-terminated side treated with copper(II) acetate monohydrate, keep it for 20 s, and then rinse with 100,000 mg deionized water, then rinse with 50,000 mg anhydrous ethanol, and vacuum dry at 80 °C for 20 min; Step 7: Take a 100mm×100mm low-profile electrolytic copper foil, rinse it with 30,000mg of anhydrous ethanol, then rinse it with 100,000mg of deionized water, and dry it at 80℃ for 10min; add 10mg of 1,2,3-benzotriazole to a mixture of 70,000mg of anhydrous ethanol and 30,000mg of deionized water, stir for 10min to form a 1,2,3-benzotriazole treatment solution; immerse the copper foil to be pressed into the 1,2,3-benzotriazole treatment solution for 20s, take it out and rinse it with 20,000mg of anhydrous ethanol, and dry it at 80℃ for 10min; Step 8: Dry the film obtained in Step 6 under vacuum at 120°C for 30 min. Lay the catechol-terminated side treated in Step 6 with the copper foil side to be pressed in Step 7. Place the laminate in a vacuum hot press and evacuate to an absolute pressure below 500 Pa. Preheat at 160°C and 0 MPa for 10 min, and then press at 230°C and 1.5 MPa for 20 min. After pressing, cool to below 80°C while maintaining pressure, and remove to obtain the polyimide film and copper foil composite for integrated circuit copper-clad laminates. Example 3:

[0026] This embodiment takes the preparation of a 100mm×100mm single-sided lamination evaluation polyimide film and copper foil composite as an example, and the continuous coating production is scaled up proportionally according to the area.

[0027] Step 1: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried separately in an 80°C vacuum oven for 4 hours. After cooling, they were used under a dry nitrogen atmosphere. 39983 mg of anhydrous 1-methyl-2-pyrrolidone was added to a three-necked flask that had been dried at 120°C for 2 hours and cooled to room temperature. The solvent temperature was controlled between 5°C and 10°C. 3202 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added, and the mixture was stirred for 60 minutes until the solid was completely dissolved. Subsequently, 2665 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 1177 mg of 1,4'-diaminobiphenyl were added in three batches. 3,3',4,4'-Biphenyltetracarboxylic dianhydride was added to each batch and stirred for 30 minutes before adding the next batch. After all the materials were added, the temperature was raised to 25°C and stirred for 12 hours to obtain the polyamic acid solution for the main layer. Step 2: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried in a vacuum oven at 80°C for 4 hours. After cooling, they were used under the protection of dry nitrogen. 21539 mg of anhydrous 1-methyl-2-pyrrolidone was added to another three-necked flask purged with dry nitrogen. The temperature was controlled at 5°C to 10°C. 320 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added and stirred for 40 min. Then 320 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 141 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added and stirred at 25°C for 8 hours to obtain an interfacial polyamic acid solution. Step 3: Take 2500 mg of the polyamic acid solution of the main layer obtained in Step 1, invert it onto a glass plate that has been cleaned with anhydrous ethanol and dried at 120°C for 30 min, and cast it into a film in the same direction with a 200 μm doctor blade gap. Remove the excess solution with the doctor blade and do not recycle it. Place the cast film on an 80°C hot stage and heat it for 25 min, then place it on a 120°C hot stage and heat it for 15 min. The residual solvent content of the pre-baked film is measured to be 18% by weighing. Then take 120 mg of the polyamic acid solution of the interface layer obtained in Step 2, coat it once on the upper surface of the pre-baked film with a 15 μm wire rod, and heat it at 80°C for 10 min to obtain an asymmetric laminated wet film with dianhydride end groups enriched in the interface layer polyamic acid on only one side. Step 4: Place the asymmetric laminated wet film obtained in Step 3 along with the glass plate in a nitrogen oven and heat it according to the following temperature program: 80℃ for 30 min, 150℃ for 30 min, 220℃ for 30 min, 300℃ for 30 min, and 310℃ for 20 min. After the treatment, cool it to below 60℃ in a nitrogen atmosphere and peel the film off the glass plate to obtain an asymmetric polyimide film with a thickness of 27.4 μm. Step 5: Add 70,000 mg of anhydrous ethanol, 30,000 mg of anhydrous 1-methyl-2-pyrrolidone, 700 mg of dopamine hydrochloride, and 400 mg of triethylamine to a brown beaker. Stir for 20 min under dry nitrogen protection and at 25°C in the dark to obtain a dopamine treatment solution. With the dianhydride end-group enriched side of the asymmetric polyimide film obtained in Step 4 facing upward, take 1,000 mg of the dopamine treatment solution and evenly coat it on this side. Keep it at 55°C under dry nitrogen protection for 8 min. Then rinse it with 50,000 mg of anhydrous ethanol for the first time, and then rinse it with 50,000 mg of anhydrous ethanol for the second time. After that, vacuum dry at 60°C for 30 min, and then vacuum dry at 150°C for 20 min to obtain a polyimide film with catechol end-group enriched on the copper side. Step 6: Add 40 mg of copper(II) acetate monohydrate to a mixture of 80,000 mg anhydrous ethanol and 20,000 mg deionized water, and stir for 10 min to form a copper(II) acetate monohydrate treatment solution; take 500 mg of the copper(II) acetate monohydrate treatment solution and coat it onto the catechol-terminated side of the film obtained in Step 5, keep it for 90 s, and then rinse with 50,000 mg anhydrous ethanol; then add 20 mg of disodium ethylenediaminetetraacetate dihydrate to 100,000 mg deionized water, and stir for 10 min to form a disodium ethylenediaminetetraacetate dihydrate treatment solution; take 500 mg of the disodium ethylenediaminetetraacetate dihydrate treatment solution and coat it onto the catechol-terminated side treated with copper(II) acetate monohydrate, keep it for 60 s, and then rinse with 100,000 mg deionized water, then rinse with 50,000 mg anhydrous ethanol, and vacuum dry at 80 °C for 20 min; Step 7: Take a 100mm×100mm low-profile electrolytic copper foil, rinse it with 30,000mg of anhydrous ethanol, then rinse it with 100,000mg of deionized water, and dry it at 80℃ for 10min; add 40mg of 1,2,3-benzotriazole to a mixture of 70,000mg of anhydrous ethanol and 30,000mg of deionized water, and stir for 10min to form a 1,2,3-benzotriazole treatment solution; immerse the copper foil to be pressed into the 1,2,3-benzotriazole treatment solution for 60s, take it out, rinse it with 20,000mg of anhydrous ethanol, and dry it at 80℃ for 10min; Step 8: Dry the film obtained in Step 6 under vacuum at 120℃ for 30 min. Lay the catechol-terminated side treated in Step 6 with the copper foil side to be pressed in Step 7. Place the laminate in a vacuum hot press and evacuate to an absolute pressure below 500 Pa. Preheat at 160℃ and 0 MPa for 10 min, and then press at 250℃ and 2.5 MPa for 40 min. After pressing, cool to below 80℃ while maintaining pressure, and remove to obtain the polyimide film and copper foil composite for integrated circuit copper-clad laminates. Example 4:

[0028] This embodiment takes the preparation of a 100mm×100mm single-sided lamination evaluation polyimide film and copper foil composite as an example, and the continuous coating production is scaled up proportionally according to the area.

[0029] Step 1: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried separately in an 80°C vacuum oven for 4 hours. After cooling, they were used under a dry nitrogen atmosphere. 38641 mg of anhydrous 1-methyl-2-pyrrolidone was added to a three-necked flask that had been dried at 120°C for 2 hours and cooled to room temperature. The solvent temperature was controlled between 5°C and 10°C. 3202 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added, and the mixture was stirred for 60 minutes until the solid was completely dissolved. Subsequently, 1999 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 1618 mg of 1,4'-diaminobiphenyl were added in three batches. 3,3',4,4'-Biphenyltetracarboxylic dianhydride was added to each batch and stirred for 30 minutes before adding the next batch. After all the materials were added, the temperature was raised to 25°C and stirred for 12 hours to obtain the polyamic acid solution for the main layer. Step 2: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried in a vacuum oven at 80°C for 4 hours. After cooling, they were used under the protection of dry nitrogen. 30502 mg of anhydrous 1-methyl-2-pyrrolidone was added to another three-necked flask purged with dry nitrogen. The temperature was controlled at 5°C to 10°C. 320 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added and stirred for 40 min. Then 220 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 178 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added and stirred at 25°C for 8 hours to obtain an interfacial polyamic acid solution. Step 3: Take 2500 mg of the polyamic acid solution of the main layer obtained in Step 1, invert it onto a glass plate that has been cleaned with anhydrous ethanol and dried at 120°C for 30 min, and cast it into a film in the same direction with a 200 μm doctor blade gap. Remove the excess solution with the doctor blade and do not recycle it. Place the cast film on an 80°C hot stage and heat it for 32 min, then place it on a 120°C hot stage and heat it for 23 min. The residual solvent content of the pre-baked film is measured to be 14% by weighing. Then take 80 mg of the polyamic acid solution of the interface layer obtained in Step 2, coat it once on the upper surface of the pre-baked film with an 8 μm wire rod, and heat it at 80°C for 10 min to obtain an asymmetric laminated wet film with dianhydride end groups enriched in the interface layer polyamic acid on only one side. Step 4: Place the asymmetric laminated wet film obtained in Step 3 along with the glass plate in a nitrogen oven and heat it according to the following temperature program: 80℃ for 30 min, 150℃ for 30 min, 220℃ for 30 min, 300℃ for 30 min, and 310℃ for 20 min. After the treatment, cool it to below 60℃ in a nitrogen atmosphere and peel the film off the glass plate to obtain an asymmetric polyimide film with a thickness of 26.0 μm. Step 5: Add 70,000 mg of anhydrous ethanol, 30,000 mg of anhydrous 1-methyl-2-pyrrolidone, 400 mg of dopamine hydrochloride, and 220 mg of triethylamine to a brown beaker. Stir for 20 min under dry nitrogen protection and at 25°C in the dark to obtain a dopamine treatment solution. With the dianhydride end-group enriched side of the asymmetric polyimide film obtained in Step 4 facing upward, take 1,000 mg of the dopamine treatment solution and evenly coat it on this side. Keep it at 40°C under dry nitrogen protection for 4 min. Then rinse it with 50,000 mg of anhydrous ethanol for the first time, and then rinse it with 50,000 mg of anhydrous ethanol for the second time. After that, vacuum dry at 60°C for 30 min, and then vacuum dry at 150°C for 20 min to obtain a polyimide film with catechol end-group enriched on the copper side. Step 6: Add 15 mg of copper(II) acetate monohydrate to a mixture of 80,000 mg anhydrous ethanol and 20,000 mg deionized water, and stir for 10 min to form a copper(II) acetate monohydrate treatment solution; take 500 mg of the copper(II) acetate monohydrate treatment solution and coat it onto the catechol-terminated side of the film obtained in Step 5, hold for 45 s, and then rinse with 50,000 mg anhydrous ethanol; then add 8 mg of disodium ethylenediaminetetraacetate dihydrate to 100,000 mg deionized water, and stir for 10 min to form a disodium ethylenediaminetetraacetate dihydrate treatment solution; take 500 mg of the disodium ethylenediaminetetraacetate dihydrate treatment solution and coat it onto the catechol-terminated side treated with copper(II) acetate monohydrate, hold for 25 s, and then rinse with 100,000 mg deionized water, then rinse with 50,000 mg anhydrous ethanol, and vacuum dry at 80 °C for 20 min; Step 7: Take a 100mm×100mm low-profile electrolytic copper foil, rinse it with 30,000mg of anhydrous ethanol, then rinse it with 100,000mg of deionized water, and dry it at 80℃ for 10min; add 15mg of 1,2,3-benzotriazole to a mixture of 70,000mg of anhydrous ethanol and 30,000mg of deionized water, stir for 10min to form a 1,2,3-benzotriazole treatment solution; immerse the copper foil to be pressed into the 1,2,3-benzotriazole treatment solution for 25s, take it out and rinse it with 20,000mg of anhydrous ethanol, and dry it at 80℃ for 10min; Step 8: Dry the film obtained in Step 6 under vacuum at 120℃ for 30 min. Lay the catechol-terminated side treated in Step 6 with the copper foil side to be pressed in Step 7. Place the laminate in a vacuum hot press and evacuate to an absolute pressure below 500 Pa. Preheat at 160℃ and 0 MPa for 10 min, and then press at 235℃ and 1.8 MPa for 25 min. After pressing, cool to below 80℃ while maintaining pressure, and remove to obtain the polyimide film and copper foil composite for integrated circuit copper-clad laminate. Example 5:

[0030] This embodiment takes the preparation of a 100mm×100mm single-sided lamination evaluation polyimide film and copper foil composite as an example, and the continuous coating production is scaled up proportionally according to the area.

[0031] Step 1: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried separately in an 80°C vacuum oven for 4 hours. After cooling, they were used under a dry nitrogen atmosphere. 39491 mg of anhydrous 1-methyl-2-pyrrolidone was added to a three-necked flask that had been dried at 120°C for 2 hours and cooled to room temperature. The solvent temperature was controlled between 5°C and 10°C. 3202 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added, and the mixture was stirred for 60 minutes until the solid was completely dissolved. Subsequently, 2443 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 1324 mg of 1,4'-diaminobiphenyl were added in three batches. 3,3',4,4'-Biphenyltetracarboxylic dianhydride was added to each batch and stirred for 30 minutes before adding the next batch. After all the materials were added, the temperature was raised to 25°C and stirred for 12 hours to obtain the polyamic acid solution for the main layer. Step 2: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride were dried in a vacuum oven at 80°C for 4 hours. After cooling, they were used under the protection of dry nitrogen. 24349 mg of anhydrous 1-methyl-2-pyrrolidone was added to another three-necked flask purged with dry nitrogen. The temperature was controlled between 5°C and 10°C. 320 mg of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl was added and stirred for 40 min. Then 281 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 152 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added and stirred at 25°C for 8 hours to obtain an interfacial polyamic acid solution. Step 3: Take 2500 mg of the polyamic acid solution of the main layer obtained in Step 1, invert it onto a glass plate that has been cleaned with anhydrous ethanol and dried at 120°C for 30 min, and cast it into a film in the same direction with a 200 μm doctor blade gap. Remove the excess solution with the doctor blade and do not recycle it. Place the cast film on an 80°C hot stage and heat it for 27 min, then place it on a 120°C hot stage and heat it for 17 min. The residual solvent content of the pre-baked film is measured to be 17% by weighing. Then take 110 mg of the polyamic acid solution of the interface layer obtained in Step 2, coat it once on the upper surface of the pre-baked film with a 12 μm wire rod, and heat it at 80°C for 10 min to obtain an asymmetric laminated wet film with dianhydride end groups enriched in the interface layer polyamic acid on only one side. Step 4: Place the asymmetric laminated wet film obtained in Step 3 along with the glass plate in a nitrogen oven and heat it according to the following temperature program: 80℃ for 30 min, 150℃ for 30 min, 220℃ for 30 min, 300℃ for 30 min, and 310℃ for 20 min. After the treatment, cool it to below 60℃ in a nitrogen atmosphere and peel the film off the glass plate to obtain an asymmetric polyimide film with a thickness of 27.0 μm. Step 5: Add 70,000 mg of anhydrous ethanol, 30,000 mg of anhydrous 1-methyl-2-pyrrolidone, 600 mg of dopamine hydrochloride, and 340 mg of triethylamine to a brown beaker. Stir for 20 min under dry nitrogen protection and at 25°C in the dark to obtain a dopamine treatment solution. With the dianhydride end-group enriched side of the asymmetric polyimide film obtained in Step 4 facing upward, take 1,000 mg of the dopamine treatment solution and evenly coat it on this side. Keep it at 50°C under dry nitrogen protection for 7 min. Then rinse it with 50,000 mg of anhydrous ethanol for the first time, and then rinse it with 50,000 mg of anhydrous ethanol for the second time. After that, vacuum dry at 60°C for 30 min, and then vacuum dry at 150°C for 20 min to obtain a polyimide film with catechol end-group enriched on the copper side. Step 6: Add 30 mg of copper(II) acetate monohydrate to a mixture of 80,000 mg of anhydrous ethanol and 20,000 mg of deionized water, and stir for 10 min to form a copper(II) acetate monohydrate treatment solution; take 500 mg of the copper(II) acetate monohydrate treatment solution and coat it onto the catechol-terminated side of the film obtained in Step 5, keep it for 75 s, and then rinse with 50,000 mg of anhydrous ethanol; then add 15 mg of disodium ethylenediaminetetraacetate dihydrate to 100,000 mg of deionized water, and stir for 10 min to form a disodium ethylenediaminetetraacetate dihydrate treatment solution; take 500 mg of the disodium ethylenediaminetetraacetate dihydrate treatment solution and coat it onto the catechol-terminated side treated with copper(II) acetate monohydrate, keep it for 45 s, and then rinse with 100,000 mg of deionized water, then rinse with 50,000 mg of anhydrous ethanol, and vacuum dry at 80 °C for 20 min; Step 7: Take a 100mm×100mm low-profile electrolytic copper foil, rinse with 30,000mg anhydrous ethanol, then rinse with 100,000mg deionized water, and dry at 80℃ for 10min; add 30mg of 1,2,3-benzotriazole to a mixture of 70,000mg anhydrous ethanol and 30,000mg deionized water, stir for 10min to form a 1,2,3-benzotriazole treatment solution; immerse the copper foil to be pressed into the 1,2,3-benzotriazole treatment solution for 45s, remove it, rinse with 20,000mg anhydrous ethanol, and dry at 80℃ for 10min; Step 8: Dry the film obtained in Step 6 under vacuum at 120°C for 30 min. Lay the catechol-terminated side treated in Step 6 with the copper foil side to be pressed in Step 7. Place the laminate in a vacuum hot press and evacuate to an absolute pressure below 500 Pa. Preheat at 160°C and 0 MPa for 10 min, and then press at 245°C and 2.2 MPa for 35 min. After pressing, cool to below 80°C while maintaining pressure, and remove to obtain the polyimide film and copper foil composite for integrated circuit copper-clad laminates.

[0032] Comparative Example 1: The difference from Example 1 is that the preparation of the interfacial polyamic acid solution in step 2 of Example 1 is not performed, and the interfacial polyamic acid solution is not coated on the upper surface of the pre-baked polyamic acid film of the main body layer in step 3 of Example 1; steps 5 and 6 of Example 1 still process the side corresponding to the upper surface of the pre-baked film in step 3 of Example 1. The remaining conditions are the same as in Example 1.

[0033] Comparative Example 2: The difference from Example 1 is that the 235 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 178 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride in step 2 of Example 1 were replaced with 222 mg of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 147 mg of 3,3',4,4'-biphenyltetracarboxylic dianhydride, respectively. Furthermore, the 28,587 mg of anhydrous 1-methyl-2-pyrrolidone in step 2 of Example 1 was replaced with 27,000 mg of anhydrous 1-methyl-2-pyrrolidone, so that the diamine and dianhydride in the polyamic acid solution of the interfacial layer were approximately equimolar and the solid content was similar to that of Example 1. All other conditions were the same as in Example 1.

[0034] Comparative Example 3: The difference from Example 1 is that, instead of heating at 80°C for 30 minutes and then heating at 120°C for 20 minutes in step 3 of Example 1, the process is changed to heating at 80°C for 45 minutes and then heating at 120°C for 35 minutes. The residual solvent content of the pre-baked film was measured to be 8% by weighing. All other conditions are the same as in Example 1.

[0035] Comparative Example 4: The difference from Example 1 is that, instead of heating at 80°C for 30 minutes and then heating at 120°C for 20 minutes in step 3 of Example 1, the process is changed to heating at 80°C for 15 minutes and then heating at 120°C for 8 minutes. The residual solvent content of the pre-baked film was measured to be 24% by weighing. All other conditions are the same as in Example 1.

[0036] Comparative Example 5: The difference from Example 1 is that the coating process of the dopamine treatment solution in step 5 of Example 1 is performed after the asymmetric laminated wet film obtained in step 3 of Example 1 and before the thermal imidization in step 4 of Example 1. After step 4 of Example 1 is completed, the coating process of the dopamine treatment solution described in step 5 of Example 1 is no longer performed. The other conditions are the same as in Example 1.

[0037] Comparative Example 6: The difference from Example 1 is that: in step 5 of Example 1, 500 mg of dopamine hydrochloride is not added to the dopamine treatment solution, and the amount of anhydrous ethanol is changed from 70,000 mg to 70,500 mg, while the amounts of triethylamine and anhydrous 1-methyl-2-pyrrolidone remain unchanged. The remaining conditions are the same as in Example 1.

[0038] Comparative Example 7: The difference from Example 1 is that: in step 6 of Example 1, 20 mg of copper(II) acetate monohydrate was not added to the copper(II) acetate monohydrate treatment solution, and the amount of deionized water was changed from 20000 mg to 20020 mg, while the amount of anhydrous ethanol remained unchanged. The other conditions were the same as in Example 1.

[0039] Comparative Example 8: The difference from Example 1 is that in Step 6 of Example 1, 10 mg of disodium ethylenediaminetetraacetate dihydrate is not added to the treatment solution, and the amount of deionized water is changed from 100,000 mg to 1,000,10 mg. The other conditions are the same as in Example 1.

[0040] Comparative Example 9: The difference from Example 1 is that in step 7 of Example 1, 20 mg of 1,2,3-benzotriazole is not added to the 1,2,3-benzotriazole treatment solution, and the amount of anhydrous ethanol is changed from 70,000 mg to 70,020 mg, while the amount of deionized water remains unchanged. The remaining conditions are the same as in Example 1.

[0041] Comparative Example 10: The difference from Example 1 is that the order of treatment with copper(II) acetate monohydrate and ethylenediaminetetraacetic acid disodium salt dihydrate in step 6 of Example 1 is reversed. Specifically, the ethylenediaminetetraacetic acid disodium salt dihydrate is first applied to the catechol-terminated side of the film obtained in step 5 of Example 1 and held for 30 seconds, and then the copper(II) acetate monohydrate is applied to that side and held for 60 seconds. The remaining conditions are the same as in Example 1.

[0042] Performance testing: Polyimide film-copper foil composites were prepared according to Examples 1-5 and Comparative Examples 1-10, with at least three 100mm × 100mm samples prepared for each group. All samples were equilibrated for 24 hours in a constant temperature and humidity environment of 23°C and 50% relative humidity before testing. Samples used for 90° peel strength and 90° peel strength after damp heat testing directly used the obtained polyimide film-copper foil composites. For samples used for dielectric properties, linear thermal expansion coefficient, and volume resistivity testing, the copper foil side of the composite was first immersed in a 25°C, 100g / L ammonium persulfate aqueous solution until the copper foil was completely removed. Then, it was rinsed three times with deionized water for 60 seconds each time, followed by rinsing once with anhydrous ethanol, and then vacuum dried at 80°C for 2 hours to obtain the copper-removed polyimide film.

[0043] 10GHz Relative Permittance and Loss Tangent Test: The test was conducted according to GB / T 43801-2024 "Test Method for Relative Permittance and Loss Tangent of Copper-Clad Laminates in Microwave Band - Separated Dielectric Resonator Method". A 50mm diameter circular sample was cut from the center of the polyimide film after copper removal and equilibrated for 24 hours at 23℃ and 50% relative humidity. The test frequency was set to 10GHz and the test temperature to 23℃. The sample was placed in the separated dielectric resonator test fixture, and the sample thickness measured with a micrometer was entered. The relative permittivity and loss tangent were measured. Three samples were tested in each group, with each sample being clamped twice. The average value of all valid test results was taken.

[0044] Initial 90° Peel Strength Test: The 90° peel strength test was conducted according to GB / T 13557-2017 "Test Methods for Flexible Copper-Clad Foil Materials for Printed Circuits". A polyimide film and copper foil composite was used. A 3.0 mm wide copper foil peel strip with an 80 mm length was prepared on the copper foil side using a precision tool, with a pre-peel of 10 mm at the starting end. The polyimide film side was fixed to the horizontal platform of a 90° peel fixture. The copper foil peel strip was clamped in the fixture of a tensile testing machine. The peel speed was set to 50 mm / min, and the test temperature was 23℃. The stable peel force within the peel stroke range of 20-60 mm was recorded and converted to peel strength per unit width. Five peel strips were tested for each sample group, and the average value was taken.

[0045] 90° Peel Strength Test after Damp Heat: Damp heat treatment was performed according to GB / T 2423.3-2016 "Environmental Testing Part 2: Test Methods - Cab: Constant Damp Heat Test", and the 90° peel strength after damp heat was tested according to GB / T 13557-2017 "Test Methods for Flexible Copper-Clad Foil Materials for Printed Circuits". Polyimide film and copper foil composites were placed in a constant temperature and humidity chamber at 85℃ and 85% relative humidity for 168 hours. After treatment, the samples were removed and allowed to recover for 2 hours at 23℃ and 50% relative humidity. Subsequently, copper foil peel strips with a width of 3.0 mm were prepared, and the 90° peel strength was tested at a peeling speed of 50 mm / min. Five peel strips were tested for each group of samples, and the average value was taken.

[0046] Linear thermal expansion coefficient test: The linear thermal expansion coefficient was tested according to GB / T 36800.2-2018 "Plastics Thermomechanical Analysis (TMA) Part 2: Determination of Linear Thermal Expansion Coefficient and Glass Transition Temperature". Copper-removed polyimide films were cut into 20mm × 5mm pieces along the casting direction, vacuum dried at 120℃ for 2 hours, and then cooled to room temperature. The tensile mode of a thermomechanical analyzer was used for testing, with a clamping length of 10mm, a constant tensile force of 0.05N, a nitrogen flow rate of 50mL / min, a heating rate of 5℃ / min, and a test temperature range of 30-300℃. The linear thermal expansion coefficient was calculated from the slope of the dimensional change curve within the 50-250℃ range. Three samples were tested for each group, and the average value was taken.

[0047] Volume resistivity test: The volume resistivity test was conducted according to GB / T 31838.2-2019 "Dielectric and resistive properties of solid insulating materials - Part 2: Resistive properties (DC method) - Volume resistivity and volume resistivity". The polyimide film after copper removal was cut into 60mm × 60mm test pieces and equilibrated for 24 hours at 23℃ and 50% relative humidity. The three-electrode method was used, with the upper electrode having an effective diameter of 50mm. The guard electrode was coaxially positioned with the upper electrode. A DC voltage of 100V was applied, and the stable current was read after 60 seconds. The volume resistivity was calculated based on the sample thickness.

[0048] Table 1 Performance Test Results Example 1 2.95 0.0042 1.24 1.08 21.5 8.4 Example 2 3.02 0.0048 0.98 0.81 20.8 9.1 Example 3 2.84 0.0036 1.36 1.18 23.2 7.2 Example 4 2.99 0.0045 1.10 0.92 21.1 8.9 Example 5 2.89 0.0039 1.31 1.13 22.7 7.7 Comparative Example 1 2.92 0.0041 0.56 0.34 20.9 9.6 Comparative Example 2 2.96 0.0044 0.73 0.51 21.4 8.7 Comparative Example 3 2.95 0.0042 0.82 0.60 21.2 9.2 Comparative Example 4 3.04 0.0058 0.89 0.55 24.3 4.8 Comparative Example 5 3.07 0.0056 0.84 0.57 22.6 5.4 Comparative Example 6 2.94 0.004 0.66 0.43 21.2 9.5 Comparative Example 7 2.96 0.0042 0.96 0.75 21.4 9.0 Comparative Example 8 3.03 0.0067 1.20 0.71 22.1 2.4 Comparative Example 9 2.97 0.0046 1.17 0.65 21.7 6.9 Comparative Example 10 3.02 0.0062 1.14 0.68 22.0 2.8 As shown in Table 1, Comparative Example 1, which did not have a dianhydride end-group enrichment interface layer, had a loss tangent of 0.0041 at 10 GHz and a volume resistivity of 9.6 × 10⁻⁶. 16 The initial 90° peel strength and the 90° peel strength after damp heat were only 0.56 N / mm and 0.34 N / mm, respectively, indicating that it is difficult to form a stable bonding interface on low profile copper foil by relying solely on the surface treatment of the main polyimide.

[0049] Comparative Examples 2 to 4 were used to change the end-group state of the interface layer and the residual solvent content of the pre-baked substrate layer, respectively. In Comparative Example 2, the peel strength improvement was limited due to insufficient dianhydride end-groups in the interface layer. In Comparative Example 3, the interdiffusion between the interface layer and the substrate layer was insufficient due to the low residual solvent content of the pre-baked film. In Comparative Example 4, the 10GHz loss tangent increased to 0.0058 due to the high residual solvent content, and the peel strength decreased to 0.55 N / mm after wet heating, indicating that there is a suitable residual solvent window in the interface layer formation process.

[0050] Comparative Example 5 advanced the dopamine treatment before thermal imidization, while Comparative Example 6 did not add dopamine hydrochloride. The peel strength and wet-heat peel strength of both were lower than those of Example 1, indicating that the unilateral dopamine grafting treatment after thermal imidization is beneficial for introducing catechol end groups that can participate in interfacial bonding on the copper side.

[0051] Comparative Example 7, without copper(II) acetate monohydrate loading, had an initial 90° peel strength of 0.96 N / mm, still lower than Example 1. Comparative Example 8, without ethylenediaminetetraacetic acid disodium salt dihydrate complex peeling, achieved an initial peel strength of 1.20 N / mm, but the 10GHz loss tangent increased to 0.0067, and the volume resistivity decreased to 2.4 × 10⁻⁶. 16 The value of Ω·cm indicates that while simply increasing the number of copper species at the interface is beneficial for initial adhesion, it is detrimental to dielectric stability and damp heat reliability.

[0052] In Comparative Example 9, without 1,2,3-benzotriazole weak passivation, the peel strength at 90° after wet heat decreased from 1.08 N / mm in Example 1 to 0.65 N / mm. In Comparative Example 10, when the treatment with disodium ethylenediaminetetraacetate dihydrate was placed before the treatment with copper(II) acetate monohydrate, an increase in loss tangent and a decrease in peel strength after wet heat were also observed.

[0053] Compared with the comparative examples above, Examples 1 to 5, within a low-loss range of 2.84-3.02 relative permittivity at 10 GHz and 0.0036-0.0048 loss tangent at 10 GHz, simultaneously achieved an initial 90° peel strength of 0.98-1.36 N / mm, a 90° peel strength after damp heat of 0.81-1.18 N / mm, a linear coefficient of thermal expansion of 20.8-23.2 ppm / ℃, and a coefficient of thermal expansion of 7.2 × 10⁻⁶. 16 -9.1×10 16The volume resistivity is measured in Ω·cm. Among them, Example 3 exhibits the lowest 10GHz loss tangent, the highest initial 90° peel strength, and the highest 90° peel strength after damp heat. This indicates that increasing the proportion of fluorinated dianhydride, combined with a thicker dianhydride end-group enriched interface layer, unilateral dopamine grafting after thermal imidization, complexation peeling after copper ion loading, and weak passivation treatment of copper foil, can improve the interfacial bonding between low-profile copper foil and polyimide film without significantly sacrificing volume insulation.

[0054] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A thin film used on copper-clad laminates of integrated circuits, characterized in that, It includes a polyimide body layer and a copper-side interface layer formed only on one side of the polyimide body layer; Based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, the polyimide host layer is formed by thermal imidization of a host layer polyamic acid comprising 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 55.5-83.2 parts by weight of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 36.8-55.1 parts by weight of 3,3',4,4'-biphenyltetracarboxylic dianhydride; Based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, the copper-side interface layer is formed of a dianhydride-end-rich interface layer polyamic acid comprising 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 58.4-100 parts by weight of 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 44.1-57.8 parts by weight of 3,3',4,4'-biphenyltetracarboxylic dianhydride; The copper-side interface layer is formed by coating the dianhydride-end-group-enriched interface layer polyamic acid on one side of the pre-baked film and thermally imidizing it together with the polyamic acid of the main layer when the residual solvent content of the pre-baked film formed by the polyamic acid of the main layer is 12%-18%. The outer surface of the copper-side interface layer is an interface-activated surface formed by enriching catechol end groups through treatment with dopamine / triethylamine hydrochloride after thermal imidization, and by ethylenediaminetetraacetic acid complexation and exfoliation after loading with copper(II) salt. The molar ratio of total dianhydride monomers to 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl in the main polyamic acid layer is 0.98-1.02:1, and the molar ratio of total dianhydride monomers to 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl in the dianhydride-end-group enriched interface polyamic acid layer is 1.05-1.20:

1.

2. The thin film used on copper-clad laminates of integrated circuits according to claim 1, characterized in that, The main layer polyamic acid is obtained by polymerization of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride in anhydrous 1-methyl-2-pyrrolidone; the anhydrous 1-methyl-2-pyrrolidone is 1193-1249 parts by weight based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

3. The thin film used on an integrated circuit copper-clad laminate according to claim 1, characterized in that, The dianhydride-terminated enriched interfacial polyamic acid is obtained by polymerization of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride in anhydrous 1-methyl-2-pyrrolidone; the anhydrous 1-methyl-2-pyrrolidone is 6731-10596 parts by weight, based on 100 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

4. The thin film used on an integrated circuit copper-clad laminate according to claim 1, characterized in that, The pre-baked film is obtained by casting the main layer of polyamic acid into a film, and then heating it sequentially at 80°C for 25-35 minutes and at 120°C for 15-25 minutes.

5. The thin film used on copper-clad laminates of integrated circuits according to claim 1, characterized in that, The coating mass ratio of the dianhydride-end-rich interface layer polyamic acid to the host layer polyamic acid is 60-120:2500, and the dianhydride-end-rich interface layer polyamic acid is coated on one side of the pre-baked film using 5-15μm wire rods.

6. The thin film used on copper-clad laminates of integrated circuits according to claim 1, characterized in that, The co-thermal imidization process includes: holding at 80°C for 30 min, holding at 150°C for 30 min, holding at 220°C for 30 min, holding at 300°C for 30 min, and holding at 310°C for 20 min.

7. The thin film used on an integrated circuit copper-clad laminate according to claim 1, characterized in that, The treatment solution used for the dopamine / triethylamine hydrochloride treatment includes anhydrous ethanol, anhydrous 1-methyl-2-pyrrolidone, dopamine hydrochloride, and triethylamine; by mass, the ratio of anhydrous ethanol, anhydrous 1-methyl-2-pyrrolidone, dopamine hydrochloride, and triethylamine is 70000:30000:300-700:160-400; the dopamine / triethylamine hydrochloride treatment is performed by coating the outer surface of the copper-side interface layer with the copper-side interface layer facing upwards, and maintaining it at 35-55°C under dry nitrogen protection for 3-8 minutes.

8. The thin film for use on copper-clad laminates of integrated circuits according to claim 1, characterized in that, The copper(II) salt is copper(II) acetate monohydrate, and the ethylenediaminetetraacetic acid salt is ethylenediaminetetraacetic acid disodium salt dihydrate.

9. The thin film used on an integrated circuit copper-clad laminate according to claim 1, characterized in that, The copper(II) salt loading treatment is as follows: 10-40 parts by weight of copper(II) acetate monohydrate are added to a mixture of 80,000 parts by weight of anhydrous ethanol and 20,000 parts by weight of deionized water to form a copper(II) acetate monohydrate treatment solution. The copper(II) acetate monohydrate treatment solution is then applied to the outer surface of the catechol end group enriched and kept for 30-90 seconds before rinsing. The ethylenediaminetetraacetic acid (EDTA) complexation and stripping treatment is as follows: 5-20 parts by weight of EDTA disodium salt dihydrate are added to 100,000 parts by weight of deionized water to form an EDTA disodium salt dihydrate treatment solution. The EDTA disodium salt dihydrate treatment solution is applied to the outer surface after copper(II) salt loading treatment and kept for 20-60 seconds before rinsing.